Jet engine silencer



April 21, 1959 c. R. KlLLlAN 2,882,991

JET ENGINE SILENCER Filed Sept. 2, 1955 Fig.

Ulaud E. Killian INVENTOR.

BY ym 1'3 M5"),

United States Patent JET ENGINE SILENCER Claud R. Killian, Hayesville, N.C.

Application September 2, 1955, Serial No. 532,260

2 Claims. (Cl. 181-57) This invention relates to devices for silencing internal combustion engines, and particularly to a silencer for a jet engine.

An object of this invention is to provide an engine silencer which is attached to the exhaust tube of a jet engine, the silencer being mounted in such a way that the exhaust gases pass through it, the silencer being essentially a low-pass acoustical filter.

A further object of this invention is to provide a silencer for a jet engine exhaust tube which forms very little back pressure in its silencing operation.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure l is a fragmentary sectional view of a jet engine exhaust tube to which the silencer is attached;

Figure 2 is a rear view of Figure 1; and

Figure 3 is a fragmentary longitudinal sectional view showing a modification of the silencer.

In the drawings, there is a jet engine exhaust tube at the discharge end 12 of which the silencer 14 is mounted. This silencer consists of a bulbous housing having an opening 16 at one end thereof into which the exhaust tube 10 is inserted. The opposite end of the bulbous member has a discharge opening 18 therein in registry with the discharge end of the exhaust tube 10 and slightly larger than the opening 12 thereof.

The bulbous member 14 is similar in appearance to a bell. However, the end portion 20 is flared smoothly inwardly instead of outwardly as in a bell. The inner surface 22 of the bulbous member has annular ribs or corrugations therein which constitute baflles 24. The bafiles are concentrically arranged along the longitudinal axis of the bulbous member, and when it is placed on the exhaust tube 10, these corrugations are concentric with the longitudinal axis of the exhaust tube.

As the exhaust gases from a jet engine issue from the exhaust tube 10, they spread gradually, as shown in Figure 1. The lip 26 of the bulbous member and located at the discharge opening 18 is located at the outer edge of the cone of issuing gases. Some of the gases are reflected toward the concentric line 28 extending parallel to the longitudinal axis of the exhaust tube 10 and the bulbuos member. Devious flow paths are formed in this way in order to form a mutfiing action. Additionally, the cavity formed by the bulbuos member over the outer surface of the exhaust tube 10 and the extension of the 2,882,991 Patented Apr. 21, 1959 outer surface of this tube 10 and the inner corrugated surface of the bulbous member produces considerable attenuation of sound waves above a cut-off frequency determined by the size of this cavity.

The jet engine exhaust tube 10 of Figure 3 is provided with a silencer 32 which has a hollow bulbous member 34 of a shape similar to the shape of member 20. Instead of a series of ribs which constitute baffles 24, Figure 3 has an apertured liner 36 together with a plurality of annular spacers 38 holding liner 36 spaced from the inner surface of member 34. Spacers 38 are also apertured and with apertured liner 36 constitute sound and gas baflles.

Some circulation between member 34 and liner 36 is present during the use of silencer 32. The gas is discharged through the aperture 40 around the lip 42 of the bulbous member 34. Sound waves passing between the liner 36 and member 34 are silenced as they pass through the numerous apertures.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. In combination with a jet engine exhaust tube having a discharge end from which issues exhaust gases for propulsion, a silencer attached to said tube and comprising a bulbous housing having a wall provided with a front open end in which said tube is disposed, the forward end of said wall having an aperture, the inner surface of said housing being shallowly and transversely corrugated from said aperture which is upstream of the discharge end of said tube to the rear open end of said housing to provide baffles for reflecting sound waves, the discharge end of said exhaust tube being located in said housing intermediate the front and rear open ends thereof and at a relatively short distance from said discharge end of the housing, the portion of the exhaust tube which is in said housing being spaced from the wall of said housing to constitute a cavity which forms a low-pass acoustical filter for attenuating the sound waves.

2. The combination of claim 1 and the rear open end of said housing having an inwardly directed lip from which sound waves emanate.

References Cited in the file of this patent UNITED STATES PATENTS 1,607,003 King Nov. 16, 1926 2,096,260 Pavillion Oct. 19, 1937 2,705,541 Finch Apr. 5, 1955 FOREIGN PATENTS 215,488 Germany Oct. 29, 1909 298,935 Germany Dec. 3, 1919 670,773 France Aug. 24, 1929 800,850 France May 11, 1936 830,201 France May 9, 1938 581,974 Great Britain Oct. 31, 1946 480,376 Canada Jan. 22, 1952 

